Advanced Configuration & Power Interface (“ACPI”, e.g., Revision 2.0b, Oct. 11, 2002) is an open industry standard specification for a platform configuration and power management scheme. ACPI-compliant operating systems (“OS”) typically interact with platform hardware in two ways. First, the Basic Input/Output System (“BIOS”) in the hardware may produce a set of memory resident tables which are parsed by the OS and its ACPI driver. These tables provide the root for software enumeration of all platform hardware that is not otherwise represented. Specifically, ACPI does not represent platform hardware that complies with parent bus standards (e.g., PC Interconnect, “PCI”) because this type of hardware may be enumerated and power managed using the standards. Thus, the hardware typically declared in ACPI tables are platform hardware that cannot be enumerated and/or managed using the bus standards. In other words, the ACPI tables contain an enumeration and power management abstraction for all platform specific (i.e. not bus standard) hardware in the platform.
Since platform hardware is interdependent, there can be only one “policy owner” for managing it. In a typical computing environment, an OS manages the platform resources In virtualized environments, however, multiple operating systems may have access to the resources on the platform. Virtualization technology enables a single host computer running a virtual machine monitor (“VMM”) to present multiple abstractions and/or views of the host, such that the underlying hardware of the host appears as one or more independently operating virtual machines (“VMs”). Each VM may function as a self-contained platform, running its own OS and/or a software application(s). The VMM typically manages allocation of resources on the host and performs context switching as necessary to cycle between various VMs according to a round-robin or other predetermined scheme. The VMM is therefore responsible for interacting with ACPI and to avoiding resource conflicts.